Conceitos importantes

Question 1

Genetic drift

Answer 1

Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces.

Question 2

The founder effect

Answer 2

When a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool differs from the source population; this is called the founder effect. The founder effect might occur, for example, when a few members of a population are blown by a storm to a new island. Genetic drift, in which chance events alter allele frequencies, will occur in such a case if
the storm indiscriminately transports some individuals (and their alleles), but not others, from the source population.

Question 3

The bottleneck effect

Answer 3

A sudden change in the environment, such as a fire or flood, may drastically reduce the size of a population. A severe drop in population size can cause the bottleneck effect, so named because the population has passed through a “bottleneck” that reduces its size

Question 4

Relative fitness

Answer 4

certain traits can lead to greater relative
fitness: the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals